U.S. Pat. No. 5,151,147 issued Sep. 29, 1992 describes a method and apparatus for the production of, among other continuous elongated articles, a coated magnet wire of the type used in the winding of electrical transformers. The product produced by the apparatus and method described in that patent comprises a conductive core, preferably of a metal such as copper or aluminum, surrounded by an adherent layer of an insulating polymer. In the production of transformers, multiple layers of this coated magnet wire are concentrically wound with paper or other insulating material interleaves between the sequential layers to form the core of an electrical transformer.
While the magnet wire produced by this system has proven entirely adequate and to a certain extent revolutionized the production of magnet wire based transformer systems, it can be relatively expensive to produce. The cost of such a product is in large extent affected by the cost of the polymer applied about the metallic core. This is particularly so in the case of high temperature transformers (operating temperature on the order of 200° C. or more) where the applied polymer is a so-called engineering polymer. Such materials while exhibiting excellent insulating and heat resistance properties are quite costly vis-à-vis lower temperature capability insulating polymers or other competitive insulating products.
Accordingly means to reduce the amount of polymer used in the insulating layer have been sought after for many years. The most obvious and generally simplest approach to achieving such polymer material volume reduction is, of course applying a thinner layer (on the order of 2–3 mils) of the insulating polymer. While these approaches have been successful in reducing the amount/volume of insulating polymer applied to the magnet wire to a minimum, attempts to further reduce the thickness of such coatings have, for all practical purposes, stressed the limits of the manufacturing process to further reduce the thickness of the polymeric insulating layer. Additionally, the currently applied insulating polymers have substantially reached the limits of their dielectric strength at current levels/thicknesses of application. Thus, practically, there is no currently known way to further reduce the thickness of such layers within the currently known manufacturing processes and with the currently available materials.
There thus exists a need for a method of further reducing the amount of applied insulating polymer in such products to further reduce the costs inherent in the production thereof.